Calculates the integral of a function using the Simpson's method.
| f | The function to be integrated. |
| a | L.h.s. of the integration interval. |
| b | R.h.s. of the integration interval. |
| rel_eps | (Optional, defaults to 1e-10) precision parameter. |
| max_steps | (Optional, defaults to 20) Max number of simpson interation, it implies a maximal 2^max_steps function evaluation. |
| return value | The numerical integral. |